<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title> fudng </title>
   <style>
      #parent{
          height:300px;
          width:300px;
      }
      #s1,#s2,#s3{
          height:300px;
          width:300px;

      }
       #s1{
           background-color: salmon;
           float: left;
       }
       #s2{
           background-color: skyblue;
           float: left;
       }
       #s3{
           background-color: lightskyblue;
           float: left;
       }
   </style>
</head>
<body>
<div id="parent">
    <div id="s1">1</div>
    <div id="s2">2</div>
    <div id="s3">3</div>
</div>
</body>
</html>